The invention relates to a device for the homogenization of high-viscosity fluids and also to uses of such a device.
During the extrusion and injection molding of thermoplastic materials, homogenous--particularly thermally homogenous--melts are produced using static mixers. Without special provisions plastics melts in plastification machines on leaving the screw exhibit considerable temperature differences; when coloring agents and/or additives are added, their distribution can also be irregular. In injection molding machines the necessary homogeneity of the plastics melt is obtained by the provision of a mixing head in the nozzle (see e.g. G. Schneider and R. Maurer, Osterr Kunststoff-Zeitschrift, 1985, pages 86-89).
A mixing head or melt mixer comprises a sleeve in which are situated several mixing elements. Due to the high viscosity of plastics melts large forces act on the mixing elements and also between the mixing elements and the sleeve. In a preferred embodiment of the mixing head, the mixing elements are in the form of a casting which is monolithic (i.e. cohesive without joints) and is soldered into the sleeve. Such a mixing head has the disadvantage that under extreme conditions the soldered joint may not survive. Such extreme conditions which may arise during faulty operation are, for instance: cold start (with a peak pressure of around 2000 bar), fast heating, cleaning with a naked flame, or quenching at an annealing temperature with water.